/*
 * Copyright 2008 ZXing authors
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jwetherell.quick_response_code.qrcode;

import java.util.Map;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.Writer;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.jwetherell.quick_response_code.qrcode.decoder.ErrorCorrectionLevel;
import com.jwetherell.quick_response_code.qrcode.encoder.ByteMatrix;
import com.jwetherell.quick_response_code.qrcode.encoder.Encoder;
import com.jwetherell.quick_response_code.qrcode.encoder.QRCode;


/**
 * This object renders a QR Code as a BitMatrix 2D array of greyscale values.
 * 
 * @author dswitkin@google.com (Daniel Switkin)
 */
public final class QRCodeWriter implements Writer {

    private static final int QUIET_ZONE_SIZE = 4;

    @Override
    public BitMatrix encode(String contents, BarcodeFormat format, int width, int height)
            throws WriterException {

        return encode(contents, format, width, height, null);
    }

    @Override
    public BitMatrix encode(String contents, BarcodeFormat format, int width, int height,
            Map<EncodeHintType, ?> hints) throws WriterException {

        if (contents.length() == 0) { throw new IllegalArgumentException("Found empty contents"); }

        if (format != BarcodeFormat.QR_CODE) { throw new IllegalArgumentException(
                "Can only encode QR_CODE, but got " + format); }

        if (width < 0 || height < 0) { throw new IllegalArgumentException(
                "Requested dimensions are too small: " + width + 'x' + height); }

        ErrorCorrectionLevel errorCorrectionLevel = ErrorCorrectionLevel.L;
        if (hints != null) {
            ErrorCorrectionLevel requestedECLevel = (ErrorCorrectionLevel) hints
                    .get(EncodeHintType.ERROR_CORRECTION);
            if (requestedECLevel != null) {
                errorCorrectionLevel = requestedECLevel;
            }
        }

        QRCode code = new QRCode();
        Encoder.encode(contents, errorCorrectionLevel, hints, code);
        return renderResult(code, width, height);
    }

    // Note that the input matrix uses 0 == white, 1 == black, while the output matrix uses
    // 0 == black, 255 == white (i.e. an 8 bit greyscale bitmap).
    private static BitMatrix renderResult(QRCode code, int width, int height) {
        ByteMatrix input = code.getMatrix();
        if (input == null) { throw new IllegalStateException(); }
        int inputWidth = input.getWidth();
        int inputHeight = input.getHeight();
        int qrWidth = inputWidth + (QUIET_ZONE_SIZE << 1);
        int qrHeight = inputHeight + (QUIET_ZONE_SIZE << 1);
        int outputWidth = Math.max(width, qrWidth);
        int outputHeight = Math.max(height, qrHeight);

        int multiple = Math.min(outputWidth / qrWidth, outputHeight / qrHeight);
        // Padding includes both the quiet zone and the extra white pixels to accommodate the
        // requested
        // dimensions. For example, if input is 25x25 the QR will be 33x33 including the quiet zone.
        // If the requested size is 200x160, the multiple will be 4, for a QR of 132x132. These will
        // handle all the padding from 100x100 (the actual QR) up to 200x160.
        int leftPadding = (outputWidth - (inputWidth * multiple)) / 2;
        int topPadding = (outputHeight - (inputHeight * multiple)) / 2;

        BitMatrix output = new BitMatrix(outputWidth, outputHeight);

        for (int inputY = 0, outputY = topPadding; inputY < inputHeight; inputY++, outputY += multiple) {
            // Write the contents of this row of the barcode
            for (int inputX = 0, outputX = leftPadding; inputX < inputWidth; inputX++, outputX += multiple) {
                if (input.get(inputX, inputY) == 1) {
                    output.setRegion(outputX, outputY, multiple, multiple);
                }
            }
        }

        return output;
    }

}
